FIB based open via analysis and repair

Abstract

An improved method, apparatus, and control/guiding software for localizing, characterizing, and correcting defects in integrated circuits, particularly open or resistive contact/via defects and metal bridging defects, using FIB technology. An apparatus for identifying an abnormal discontinuity in a contact/via in an integrated circuit comprising a focused ion beam system to scan the ion beam over the contact/via to do remove or deposit via material, a detector to collect a secondary particle signal from the contact/via material that gets removed, a sub-system for storing the secondary particle signal from the contact/via in time as well as x-y scan position, a sub-system for correlating secondary particle signals and identifying discontinuities in the correlated secondary particle signals, a sub-system for optimizing the display of the abnormal discontinuity; and a computer to implement software aspects of the system.

1. An apparatus for identifying an abnormal discontinuity in a vertical conducting connection (contact/via) in an integrated circuit comprising:
 a) a focused ion beam system to scan an ion beam over the contact/via so as to do at least one of: removing and depositing contact/via material; 
 b) a detector to collect a secondary particle signal from the contact/via material that gets removed; 
 c) a first sub-system for storing the secondary particle signal from the contact/via in time as well as x-y scan position; 
 d) a second sub-system for correlating secondary particle signals and identifying discontinuities in the correlated secondary particle signals; 
 e) a third sub-system for optimizing a display of the abnormal discontinuity; and 
 f) a computer configured to implement software aspects of a)-e). 
 
     
     
       2. The apparatus of  claim 1  wherein said first sub-system comprises FIB Assist hardware and software, said first sub-system providing a FIB Assist pseudo-cross section. 
     
     
       3. The apparatus of  claim 2  wherein said second sub-system is configured to highlight the FIB Assist pseudo cross section image where the discontinuity shows its largest extent in x-y and time. 
     
     
       4. A data storage medium containing a pseudo-cross-section image as in  claim 2  of a suspected defective region of an IC, on which correlation data which would allow identification of a defect is highlighted. 
     
     
       5. The apparatus of  claim 1  wherein the discontinuity is a material defect. 
     
     
       6. The apparatus of  claim 1  wherein the focused ion beam system for removal of material includes a chemistry delivery system configured to assist said removal of material by a chemistry. 
     
     
       7. The apparatus of  claim 1  wherein the secondary particles are electrons. 
     
     
       8. The apparatus of  claim 1  wherein the third subsystem is configured to use Fireflies to assist the display of the discontinuity. 
     
     
       9. The apparatus of  claim 1  wherein said computer is configured to control said scanning so that the removal of the via material extends into adjacent regions so as to produce a lateral discontinuity in the secondary particle signal. 
     
     
       10. The apparatus of  claim 9  wherein the computer is configured to control said scanning such that the scanning to remove the via material is stopped when some portion of the adjacent material shows a discontinuity which indicates a horizontal trace has been reached. 
     
     
       11. The apparatus of  claim 10  wherein said second sub-system is configured to convert time to reach said horizontal trace into a metric for placing said discontinuity as a percentage of mill time to remove said via material. 
     
     
       12. The apparatus of  claim 10  including a chemistry delivery system configured to assist said removal of material by a chemistry, wherein said chemistry delivery system is configured such that said chemistry is injected after the stopping of the removal of said via material so as to deposit conductive material into the removed via and recreate a via in place of said removed via. 
     
     
       13. The apparatus of  claim 1  including means for localizing said abnormal discontinuity in said contact/via by a defect localization methodology. 
     
     
       14. The apparatus of  claim 13  wherein said means for localizing said abnormal discontinuity in said contact/via includes a mechanical probing needle. 
     
     
       15. The apparatus of  claim 14  wherein said mechanical probing needle is sub-micron. 
     
     
       16. The apparatus of  claim 15  wherein the sub-micron probing needle is from a scanning probe microscope. 
     
     
       17. The apparatus of  claim 15  wherein the scanning probe microscope is in situ with the FIB system. 
     
     
       18. The apparatus of  claim 1  wherein said third sub-system is configured to display said abnormal discontinuity signal as a 3-d surface. 
     
     
       19. The apparatus of  claim 1  wherein said third sub-system is configured to display said abnormal discontinuity as a cross section which can actually be rotated by the user so as to inspect the nature of the discontinuity and thus classify it against a library. 
     
     
       20. The apparatus of  claim 19  wherein the scanning of the ion beam is moved to consecutive vias to investigate discontinuities in them.